多壁碳纳米管对稀土元素的吸附性能  

Adsorption of Rare Earths on Multi-Walled Carbon Nanotubes

作　　者：佟珊珊[1] 石云峰[1] 吕学举[1] 宋乃忠[1] 刘威[1] 贾琼[1] 周伟红[1] 

机构地区：[1]吉林大学化学学院,长春130022

出　　处：《应用化学》2010年第8期944-949,共6页Chinese Journal of Applied Chemistry

基　　金：吉林大学基本科研业务费资助项目(2008年)

摘　　要：研究了改性多壁碳纳米管(MWCNTs)对稀土元素的吸附。采用硝酸、次氯酸钠、过氧化氢、高锰酸钾4种方法对MWCNTs进行改性,考察了改性MWCNTs对稀土元素的吸附能力。采用紫外-可见分光光度法测定稀土元素的浓度,比较了未处理和不同方法处理的MWCNTs对稀土元素的吸附能力。实验结果表明,NaClO改性的MWCNTs对稀土元素的吸附能力最强。以稀土元素钐(Sm)、钆(Gd)、镱(Yb)为代表,详细研究了NaClO改性MWCNTs对稀土元素的吸附性能。考察了溶液pH值、离子强度、吸附剂用量、温度等因素对吸附性能的影响。当溶液pH值在2～7范围内,NaClO改性的MWCNTs对Sm、Gd、Yb的吸附随pH值增大而增强。当离子强度和MWCNTs的用量增大时,对稀土元素的吸附能力降低。3种元素在NaClO改性的MWCNTs上的吸附均为放热过程,其反应焓变ΔH分别为-6.44、-5.63和-8.31kJ/mol。吸附等温线符合Langmuir和Freundlich等温吸附方程。Modified multi-walled carbon nanotubes（MWCNTs） were chosen as adsorbents for the adsorption of rare earths. Nitric acid （ HNO3 ）,sodium hypochlorite （ NaClO ）,hydrogen peroxide （ H2 O2 ）,and potassium permanganate（ KMnO4 ） were used for the modification of MWCNTs. The concentrations of rare earths were determined with UV-Vis spectrometry. The adsorption capacities of rare earths on MWCNTs treated with different modification methods were compared with each other. The experimental results indicate that MWCNTs modified with NaClO has the highest adsorption capacity of rare earths. As representitives,the adsorptions of samarium（Sm）,gadolinium（Gd）,and ytterbium（Yb） on MWCNTs modified with NaClO were investigated in detail. Effects of various parameters such as the rare earth concentration,pH value,ion strength,amount of MWCNTs,and experimental temperature were investigated. The adsorption of Sm,Gd and Yb onto MWCNTs modified with NaClO increased with pH value in a range of 2 ～ 7. However,the adsorption capacity of the three rare earths decreased with increasing solution ion strength and MWCNTs mass. The adsorption reactions of all the three rare earths on MWCNTs modified with NaClO were exothermic processes. The thermodynamic functions,ΔH,were calculated to be - 6. 44 kJ /mol, - 5. 63 kJ /mol, - 8. 31 kJ /mol for Sm, Gd, and Yb, respectively. Furthermore, the adsorption data were fitted with Langmuir and Freundlich isotherm models,indicating that both the models can fit the adsorption of Sm,Gd, and Yb well.

关 键 词：多壁碳纳米管 改性 稀土元素 吸附 

分 类 号：O647.3[理学—物理化学]